Camptothecins, taxanes, anticancer nucleotides and such are active against a wide variety of tumor cells, and thus are expected to be useful as therapeutic agents, such as anticancer agents (Patent Documents 1 and 2). Many of these compounds are lipophilic, and because of their low water solubility, their use in injections (parenteral administration) is sometimes limited (Patent Document 1).
Water-soluble prodrugs have been studied in an attempt to solubilize such lipophilic pharmaceutical agents in water (Non-Patent document 1 and Patent Document 1).    [Patent Document 1] WO03/043631    [Patent Document 2] WO03/045952    [Non-Patent Document 1] Shan et al., J. Pharm. Sci., 86(7), 765-767, 1997